1.Invented by Alois Senefelder in 1789, a method for producing printing forms for stone printing. Using special ink or chalk, the printing copy is transferred directly onto a smooth-ground block of carbonate of lime (calcium carbonate – CaCO3).
The stone block is moistened before being inked up with oil-based printing ink. The printing areas then take up the oil-based ink, while the unchanged limestone repels it. The word lithographs (lithos for short) is also used colloquially for copy for offset printing (screened images, line engravings).
2.Lithography refers to a method of printing whereby the image areas, which are neither raised nor depressed, attract ink and the non-image areas repel ink. Most lithography is offset lithography in which the image is transferred from the plate to a rubber blanket, and then printed (offset) from the blanket onto the paper.